1. Field of the Invention
The present invention relates generally to image processing apparatus and, more particularly, to an image processing apparatus of the type which is utilized as a workstation for displaying a color image or a multi-level image or which is suitable for use in desk top publishing (DTP) or the like.
2. Description of the Related Art
In conventional apparatus of this type, it is customary to organize the constitution of memory into a plurality of image frames in order to display a multi-level image on, for example, a color workstation.
The above conventional arrangement, however, has the following disadvantages.
The first disadvantage is that a large quantity of expensive memories are required to form a multi-level image and an increase in cost is therefore incurred.
The second disadvantage is that an unnecessarily long time is required for writing or rewriting of multi-level black-and-white data or binary-level image data.
The third disadvantage consists in the fact that the conventional arrangement requires the number of frame memories which allows for an output size accommodating a plurality of image frames. For instance, if a color image is to be partially inserted into an entire document as is often the case with DTP, black-and-white data occupies a substantial portion of the image data contained in the entire document and the number of redundant portions therefore increases in the aforesaid frame memories. As a result, a large number of memories are required, thus resulting in an increase in the manufacturing cost.